Abstract
Simple SummaryAlthough Streptococcus (S). canis is mainly isolated from carnivores, intramammary infection in dairy cows caused by this bacterium have been reported. Cats and dogs with access to the barn have been considered as the main source of these infections. Here, we report subclinical mastitis and substantially increased bulk milk somatic cell counts in a dairy herd. During a herd visit, management and hygiene practices were evaluated and data from the milk quality control program were retrieved. Furthermore, quarter milk samples, mucosal swabs from farm cats and a dog, and swabs from the milking unit were aseptically collected. The samples were examined bacteriologically, and S. canis was identified using conventional phenotypic methods and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Genetic relationships between S. canis isolates were determined by multilocus sequence typing, revealing that all S. canis isolates shared the same sequence type, presenting a new combination of alleles for which a new number (ST55) was assigned. As the most likely source of intramammary infection, a farmyard cat was identified. The concurrent treatment of all positive cows and the improvement of management (no further access of carnivores to the barn) lead to positive results, including a decreased somatic cell count.The present case report provides data on the phenotypic and genotypic properties of S. canis isolated from nine dairy cows with subclinical mastitis (SCC greater than 200,000 cells/mL in the quarter milk sample, no clinical signs) and from a cat living in the barn and reports the eradication of the pathogen from the herd with an automatic milking system. The isolates were identified using conventional bacteriology, matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) and genetic relationships were investigated by multilocus sequence typing (MLST). Udder health management and hygiene instructions comprised the removal of the carnivores from the barn, strict monitoring of milking hygiene and techniques to avoid new infections via the milking robot, with simultaneous therapy for all infected cows. Phenotypic and genotypic properties of all isolates were identical. MLST revealed a unique sequence type (ST55) and a farmyard cat was identified as the most likely source of the S. canis infection in cows. The simultaneous treatment of all infected cows and management and hygiene improvements lead to a decreased SCC within four weeks.
Highlights
Streptococcus (S.) canis is a Gram-positive, catalase, and CAMP-negative streptococcal bacterium belonging to Lancefield group G
The present case report provides data on the phenotypic and genotypic properties of S. canis isolated from nine dairy cows with subclinical mastitis (SCC greater than 200,000 cells/mL in the quarter milk sample, no clinical signs) and from a cat living in the barn and reports the eradication of the pathogen from the herd with an automatic milking system
Differences or similarities between S. canis isolates can be identified via phenotypic methods or by applying genotyping techniques such as random amplified polymorphic DNA (RAPD), macrorestriction profiling using pulsed-field gel electrophoresis (PFGE), emm and scm typing and multilocus sequence typing (MLST) [6,10,12,13,14,15,16,17,18,19,20]
Summary
Streptococcus (S.) canis is a Gram-positive, catalase-, and CAMP-negative streptococcal bacterium belonging to Lancefield group G. S. canis is mainly an animal pathogen, an increasing number of human infections have been documented, with a wide range of clinical manifestations including bacteremia, urinary tract and bone infections, endocarditis and pneumonia [5,6,7,8,9,10] In dairy cows, it represents a rare but contagious pathogen causing intramammary infection (IMI) of long duration [11,12]. Infected cows usually spread the pathogen via the milking procedure, especially if udder health management is insufficient This can result in massive outbreaks of clinical and subclinical mastitis [2]. MLST has proven valuable in linking S. canis STs to host species, geographic location, time of isolation, and disease patterns (https://pubmlst.org/scanis). All isolates were phenotypically characterized and genotyped using MLST This revealed that the outbreak was caused by a single clone belonging to a novel sequence type (ST55). The eradication of the pathogen from the dairy herd with an automatic milking system is described
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
